Despite environmental advocates\u2019 belief that the decommissioning trust fund for the Humboldt Bay nuclear power plant was well-funded, the California Public Utilities Commission Feb. 27 voted without discussion to increase ratepayers\u2019 dues for burying the plant by another $400 million. There was $16.5 million on the tab for safety. This increases the total cost of completing the now-partial decommissioning to $679 million\u2014nearly doubling initial expectations. \tRegulators approved Feb. 27 without discussion the increase, with $48 million less than plant owner Pacific Gas & Electric requested. \t\u201cAlthough the revised cost is substantial, the public expects and deserves no less than appropriate clean-up of a site which has been found to have higher than expected levels of toxic contaminants\u201d including radioactive elements, notes the decision. \tPG&E estimates decommissioning costs to run up to $982 million total. Ratepayers have accrued about half that amount in burial trust funds since 1985. \tThe 63 MW plant was shut down in 1976. It cost $60 million to build and began operating in 1963. \tDecommissioning has run into two recent problems. \tThe concrete \u201cbioshield wall\u201d surrounding the reactor for protection against the elements was discovered to be contaminated. Also, managing water intrusion has turned out to be a complicated engineering problem due to its position underground next to the bay. \tThe California Coastal Commission is regulating new grading and canal work to drain and shore up the reactor area. \tThe Humboldt plant is basically a nuclear submarine turned vertically into the ground at the edge of the bay. The site now also hosts 163 MW of fossil fuel facilities that went online in 2010. \tNo final federal repository for radioactive waste exists. The spent fuel and other hazardous materials from the power plant are expected to be stored in dry casks on the edge of the bay until there is a federal site for them.